JPH0360475A - Method for bundling alumina thin tubes - Google Patents

Abstract

PURPOSE:To easily bundle porous alumina thin tubes which is difficult by the conventional method by centrifugally settling a suspension of alumina powder in an org. solvent on the end of the bundled tube, removing the org. solvent and calcining the powder at the calcination temp. of the powder. CONSTITUTION:A suspension of alumina powder in an org. solvent is centrifugally settled on the end of a bundled and joined porous alumina thin tube. The suspension is prepared by adding about 0.5-4wt.% of an org. solvent such as methanol to alumina powder. The suspension is centrifugally settled, the supernatant is decanted, and the powder is dried at about 60-80 deg.C and further air-dried. The end of the thin tube is heated at about 90-120 deg.C and sufficiently dried, and the powder is calcined at 1000-1450 deg.C for about 2-5hr to join the thin tubes. Consequently, a compact ceramic module excellent in its function as compared with that from the conventional ceramic material is produced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for bundling alumina tubes.

More specifically, the present invention relates to a method for bundling porous alumina tubes that can be used in separation membranes, bioreactors, and the like.

[Conventional technology]

It has been proposed by the present applicant and known that porous alumina tubules such as hollow fibers can be produced by dry-wet spinning and firing (for example, in Japanese Patent Application Laid-Open No. 1983-1992).
-52185, No. 62-255103, and No. 64-68520, etc.). If such porous alumina tubes are bundled together, they can be used even more effectively as separation membranes, bioreactors, etc., but there are no examples of such bundling.

Therefore, as a similar technique, we will look at an example of bundling glass tubes. In Japanese Patent Application Laid-open No. 57-160945,
A method is described in which a glass capillary is immersed in an aqueous or alcoholic solution of a metal alkoxide, gelled, and dried. However, in this method, it is extremely difficult to obtain a desired bundled article because the metal alkoxide serving as the binding agent undergoes severe volumetric shrinkage.

Furthermore, Japanese Patent Application Laid-Open No. 62-27n07 describes a mouth-passing device that uses glass tubes other than 1MJ tubes, and also shows a method for bundling glass tubes, but this method is not suitable for alumina tubes. It is essentially unapplicable. Furthermore, JP-A No. 57-16634.4 discloses a method of mixing two types of ceramics to prepare a bundling material with a small difference in thermal expansion wheel from the glass capillary, and then bundling it by thermal processing. Although shown, it is not easy to wrap this material between the capillaries.

[Problem to be solved by the invention]

An object of the present invention is to provide a method for bundling porous alumina tubes, which is considered to be completely difficult by conventional methods.

[Means to solve the problem]

The object of the present invention is to centrifugally sediment a suspension of alumina powder in an organic solvent on the ends of bundled porous alumina tubes, remove the organic solvent, and then sinter the alumina powder at the sintering temperature of the alumina powder. This is done by bundling the tubules together.

As porous alumina thin tubes, hollow fiber-like ones as described in the above-mentioned proposal publication are mainly used, and these thin tubes are bundled and subjected to a bundling process.The method of bundling them is not necessarily with a string or the like. There is no need to do this, just fit the required number into bottomed pipes of various inner diameters and stand them up.Also, before bundling, fill the thin tubes with an appropriate organic substance to prevent clogging. is commonly performed.

As the binding agent, a suspension of alumina powder in an organic solvent is used. The organic solvent suspension contains an organic solvent, such as an alcohol such as methanol or ethanol, or a ketone such as acetone or methyl ethyl ketone, in a weight ratio of about 0.5 to 4, preferably about 1 to 2, to the alumina powder. It is prepared by adding hydrocarbons such as benzene, toluene, etc., and ball milling is also performed if necessary.

Centrifugal sedimentation of an organic solvent suspension at the ends of bundled porous alumina tubes can be achieved, for example, when using the bottomed pipe described above, by fitting a number of tubes therein and suspending the organic solvent in the pipe. After pouring the liquid, it is generally rotated at a rotation speed of about 400 to 3000 gee.

Due to such high-speed rotation, the alumina powder clumps together at the lower end of the tube bundle to temporarily bind the tubes together, so after removing the supernatant organic solvent by decantation, the alumina powder is heated at about 60 to 80°C. Let it dry, remove it from the pipe, and then air dry it again. The other end of the thin tube bundle is also processed in the same manner as in step 5.

Thereafter, it is heated to about 90 to 120° C. to be sufficiently dried, and then fired generally at about 1000 to 1450° C. for about 2 to 5 hours, and the porous alumina tubes are bundled by firing. This firing is carried out in the air, in a nitrogen gas atmosphere,
This can be carried out under any atmospheric conditions such as under reduced pressure.

〔Effect of the invention〕

The method of the present invention makes it possible for the first time to bundle porous alumina tubes, resulting in the production of a ceramic module that is more functional and more compact than conventional ceramic materials. Moreover.

This ceramic module has excellent heat resistance, so it can be used in the event of clogging.

It can also be regenerated by heat treating it at about 300 to 500°C.

〔Example〕

Next, the present invention will be explained by examples.

Example 1 A suspension obtained by suspending 40 g of high-purity α-alumina (Daimei Chemical Products TM-DAR) with an average particle size of 0.2 μm in the same amount of methanol was used to prepare alumina with an outer diameter of 2 mm and a length of 12 cm. Inner diameter llIII fitted with 180 thin tube hollow fibers
Im, poured into a bottomed PVC resin pipe with an outer diameter of 13 m and a length of 12 cm to a depth of about 4CI11, 750ges
After centrifugal sedimentation by spinning for 30 minutes, the mixture was dried at 60°C. Thereafter, it was taken out from inside the pipe and air-dried for one day.

Similarly, the other end of the hollow fiber was also treated.

The hollow fiber bundle with both ends bound together in this way was first held at 90°C for 10 hours in a high-temperature furnace, and then heated to 1250°C at a heating rate of 2°C/min. After holding for a while, it was allowed to cool. The operation of flowing water at an internal pressure of 2 kgf/a+t through the thus bound hollow fiber bundle is carried out once.
Although the test was repeated 00 times, no damage was observed in the alumina tubular hollow fibers or the bundled portion.

Example 2 In Example 1, the amount of high-purity α-alumina was changed to 20 g.

Examples 3-5 In Example 1, methanol was replaced by the same amount of ethanol, acetone or toluene, respectively.

In Examples 2 to 5 as well, alumina capillary hollow fibers whose both ends were bundled were obtained.

Claims (1)

[Claims] 1. An alumina tube characterized in that a suspension of alumina powder in an organic solvent is centrifugally precipitated at the end of a bundled porous alumina tube, the organic solvent is removed, and then the alumina tube is fired at the firing temperature of the alumina powder. How to bundle.